In low-voltage circuits or low-voltage systems, respectively, or low-voltage mains, respectively, i.e. circuits for voltages of up to 1000 volts of AC voltage or 1500 volts of DC voltage, short circuits are for the most part associated with occurring arc faults, such as parallel or serial arc faults. In particular in high-performance distribution and switching systems, they can lead to disastrous destruction of operating equipment, system parts or complete switching systems, if not turned off sufficiently quickly. To avoid a longer-lasting and large-area failure of the power supply and to reduce bodily harm, it is necessary to detect such arc faults, in particular high-current or parallel arc faults, respectively, within a few milliseconds and to extinguish them. Conventional protective systems of power supply systems (e.g. fuses and circuit breakers) cannot provide reliable protection under the required time requirements.
Here, circuit breaker in particular refers to switches for low voltage. Circuit breakers are typically used, in particular in low-voltage systems, for currents of between 63 and 6300 amps. More specifically, closed circuit breakers, such as molded case circuit breakers, are used for currents of between 63 and 1600 amps, in particular of between 125 and 630 or 1200 amps. Open circuit breakers or air conduction switches, respectively, such as air circuit breakers, are in particular used for currents of between 630 and 6300 amps, more specifically of between 1200 and 6300 amps.
Circuit breakers can in particular have an electronic trip unit, identified in short as ETU.
Circuit breakers monitor the current flowing through them and interrupt the electric current or energy flow, respectively, to an energy sink or a consumer, respectively, which is identified as tripping, when current threshold values or current time span threshold values are exceeded, i.e. when a current value is present for a certain time span. The determination of tripping conditions and the tripping of a circuit breaker can take place by way of an electronic trip unit.
Short circuiters are special devices for short-circuiting lines or bars, respectively, in order to produce defined short circuits for protecting circuits or systems, respectively.
Conventional arc fault detection systems evaluate the light emission created by the arc and hereby detect the arc fault.